A liquid crystal display (LCD) panel includes two overlapping glass panels, i.e. a thin-film transistor (TFT) panel and a color filter (CF) panel. In the LCD manufacturing, after the TFT and CF panels are assembled to be a LCD panel or cell, a lighting fixture is used to inspect the basic functions of the display panel quickly and preliminarily. The lighting fixture may provide inspection-use TFTs with inspection-use signals to turn on all pixels in the display panel. The inspection-use TFTs are arranged in the edge area of the TFT panel, other than the active area in which pixel-use TFTs are arranged for image production. The inspection-use TFTs are used to control inspection-use display signals being properly provided to the pixels in the active area or display area, so that the lighting fixture can light up the LCD panel. If the LCD panel passes such a quick-inspection test, then it can be used to fabricate a LCD module. After the quick-inspection test, the gate terminals of the inspection-use TFTs have to be connected together to a DC voltage of negative value, so that the inspection-use TFTs can be disabled or turned off compulsively to avoid the electrical connections among the data lines, which may cause image failures of the display panel.
The threshold voltage Vth of a field-effect transistor is the value of the gate-source voltage when the conducting channel just begins to connect the source and drain terminals of the transistor, allowing a significantly increasing current. However, variances in the threshold voltage Vth of the TFTs may be induced by aging or during their manufacturing process. The threshold voltage Vth may get smaller and smaller to be unable to turn off the TFTs at the originally specified Vth value, causing the LCD panel to work abnormally. Therefore, it is in need to develop a new display panel to improve the reliability of the inspection-use TFTs.